[Genetic background of periodontitis. Part II. Genetic polymorphism in periodontal disease. A review of literature].

Periodontitis is an infectious disease and the majority of tissue destruction is due to the innate and adaptive immune reactions against periodontopathogenic microorganisms. Hence, genetic variations that modify immune reactions could determine individual differences. Such genetic variations may identify patients at high risk for the development of abnormal and devastating inflammatory responses. The single base variations, known as single nucleotide polymorphisms, are the most common variant. Many studies published in recent years support the evidence that genes influence the initiation and progression of periodontal disease on an individual basis. In this review article the effects of either single or composite nucleotide polymorphisms are discussed on the function of PMN leukocytes, on their immuno-receptors, the lymphokin production of inflammatory cells, and also on the function of certain structural proteins. The ethnic background of destructive periodontitis is also discussed. Since Kornman reported certain correlation between IL-1 genotype and severity of periodontitis pro-inflammatory cytokines have received the most attention and numerous papers have been published. Despite the tremendous effort of research on this field and published papers the association between different candidate gene polymorphism and its periodontal effects is still very controversial. Certain associations are dependent on sex and race, while certain previously predicted associations have not been proven later. Future studies of genetic polymorphisms in periodontics are needed, using many target genes and well defined related periodontal outcomes to determine and confirm any susceptible or resistant genes for periodontitis.